In rotating machines, misaligned shafts increase vibrations and friction, which can increase the energy consumption considerably and cause premature bearing and seal damage. Laser-based alignment systems can realize quick shaft alignment with high accuracy, consisting of laser transmitting unit, charge-coupled device (CCD) or position sensitive detector (PSD) receiving unit and display unit. Their resolution can reach 1 μm or higher, and the accuracy can be even up to ± (0.5%|L| + 1 resolution). In the paper, the principle of a laser-based alignment system is presented. In order to calibrate laser-based alignment systems, a set of measurement device is established. The receiving unit is fixed on a high precision one-dimensional linear stage, while the transmitting unit remains stationary. So, the relative displacement between the two units can be measured. A laser interferometer is used as the standard value of the linear stage displacement, which is traceable to the definition of meter. The layout of the calibration system is complied with Abbe's principle, reducing the measurement error. In addition, several key influencing factors for calibration are given. At last, the uncertainty of the calibration result is analyzed. The result indicates that the calibration apparatus is practical and efficient during the routine work.
The method of 1x asymmetry optical paths generating magnification error is employed in scale system
linear error compensation of universal tool microscope’s longitudinal coordinate.The
micro-displacements of scale iamges are achieved for compensation of scale linear error based on the
property of off-axis and out of focus and focal length inequality. The creative and ingenious optical
paths design is discribed in the paper . A detailed analysis of the principle of error compensation is
presented. Magnification error principle formula and defocus amount and off-axis aberration error
extension formula are also derived. The relationship between the calibration result and slope of formula
is obtained to benefit the analysis and application on-site.The influence caused by the change of
magnification parameters also are discussed in the paper. Indication error of one-meter longitudinal
coordinate can be achieved less than 2.5 um after compensation in using this method.
Micro-sphere is the key element in ICF (Inertial Confinement Fusion).The relative position between micro-sphere and
cylindrical gold hohlraum is required to be critically accurate so that the motivation energy and transition efficiency of
the ICF can be significantly improved. Accurate detection of micro-target assembly (especially the center position error)
is necessary and indispensable to ascertain the qualities of ignitions. The micro-sphere and cylindrical gold hohlraum
have tiny dimensions and are flimsy and easy to deform. To resolve such problems, a non-contact method based on
digital image progressing is proposed to detect the center position error of micro-sphere in this paper. Canny operator is
employed to detect the gray-level gradient image. After removing the fake edge points, the images are transformed into
binary images by a dual-threshold. To increase the operation speed, a region of interest (ROI) containing only parts of the
detected target is selected by alternating manual work. A Hough transform is then selectively applied to the chosen
sub-area. The equations of the target circles and the lines can be gotten by fitting these edge points. The center position
error of micro-sphere can be obtained based on axial and radial position errors of micro-sphere. Experimental results
show that the proposed method is independent of binary thresholds and robust to additional noises. The standard
deviation of the center position error is about 2μm, and the maximum error (3σ) is less than 6μm.
Basing on the principle of dynamic active confocal measuring method, a non-contact probe was introduced. The relation between the displacement of the object measured and the displacement of the oscillating unit was established by applying to the measure principle. To find the effect way to improve the output signal, a mathematical modal of the photoelectric signal was proposed. According to the mathematical modal, the diameter of the pinhole was decided and the optical path was adjusted, which improved the performance of the probe. It valuable to emphasize that the double lens oscillating unit was the crucial parts of the mechanical and optical structure. The tuning fork stimulating, inductive coils and the pinhole and photodiode adjuster device were designed according to the theoretical analysis, which were more convenient to the measure task. The stability of the oscillating unit was tested; and the optical and mechanical performance of the probe was validated by experiments using gage blocks combining with a micro-motion measuring mount model. The cost of a micro-displacement testing sensor was saved in designing of this kind of probe. A more accurate signal processing method was discussed in this paper.
A study on Chemical Oxygen Demand (COD) measuring method is reported, in which the COD value is measured by an integrated liquid drop monitor sensor without any reagent and chemical treatment. The integrated drop sensor consists of a liquid head, an integrated fiber sensor and a capacitor sensor. The capacitor sensor is composed of a drop head and a ring electrode. As the part of the drop head, the outline of the drop will be changed during the drop forming, which result in the variation of the capacitance. The fiber sensor is composed of two fibers that are positioned into the liquid drop. The light signal goes into the liquid drop from one fiber and out from the other one. A unique fingerprint of the liquid drop can be got by the data processing. The matching between the COD value of a liquid and the codes of the fingerprints in the database are presented and discussed.
The drop profile is one of the evident differences for different liquids. An image drop sensor is developed for capturing the drop profile images real-timely in various stages during the drop growth. The drop head for forming the uniform and satiated liquid drop is designed. The original profile records of pure water and 100% ethanol during their drop growth will be presented. Edge extraction methods on drop profile are discussed. Curve fitting based on third-order polynomial linear regression is used to mathematically describe the detected edge curves of the drop profile in sequential drop formation.
The multi-wavelength liquid signature analyzer (MWLSA) is used to analyze the characteristics of liquid. It adopts two kinds of transmitter diodes with different peak wavelengths as the light sources of the system. With MWLSA not only the light intensity signal reflecting the optical characteristic of the sample liquid under different wavelengths can be obtained, but also the volume and outline information of the corresponding liquid drop are acquirable. The application of the multi-wavelength light sources makes it possible for us to get more information about the liquid sample, which
enriches the function of the liquid signature analyzer and improves its discrimination ability of different liquids so as to have more application fields.
An on-line operation of micro-spectrometer and liquid drop analyzer is proposed in this paper. Comparing with a full spectral range spectrometer system, a micro-spectrometer has narrow spectral range that results in its inefficiency or inability in qualitative analysis of a mixed liquid since more than one function group of the mixed liquid might cause a peak or valley in the spectrogram at almost the same wavelength. A liquid drop analyzer (LDA) is an instrument that detects the characters of a liquid by monitoring its drop forming process. The LDA gives a fingerprint that is unique for certain liquid due to its specific chemical, physical and mechanical characters. An approach of combining micro-spectrometer with a fiber drop analyzer, by which a virtual 3D liquid fingerprint is formed, is described and it functions like a full range spectrum. The signals obtained from the micro-spectrometer and liquid drop analyzer, the method of on-line operation and database setting up, the experimental device and test results are described and discussed in the paper.
This paper describes a multispectral liquid drop analyzer for liquid chemical and physical properties analysis. Liquid drops formed at the tip of a liquid head are measured in parallel by a fiber sensor and a capacitive sensor. The fiber sensor works as follows: multispectral light sources are injected into the drop through an optical fiber and the total internal reflections and absorptions are detected by a photodetector. By combining fiber and capacitive sensor outputs, a drop speed independent one-dimensional waveform (liquid fingerprint) is generated. Liquid surface tension, refractive index and di-electric constant can be estimated from the fingerprint. To compare two fingerprints, the sensor outputs are normalized to have the same unit of measurement and drop starting position. After that, a reference liquid based calibration is applied to correct of fingerprint distortion due to variations in environment conditions, such as changes in temperature and humidity. Finally, a normalized correlation algorithm analyses the fingerprint difference. The repeatability and sensitivity of the system are demonstrated using different liquid samples. On-line applications show that the analyzer is able to detect 2% change in alcohol density.
An optical liquid drop sensor(OLDS) which can be used to distinguish different liquids is presented in this paper. The main block ofthis system are a light path and a drop-forming head sensor. We can gain three kinds ofiniormation about the liquid to be measured with this OLDS system. That is optical signal representing light intensity information, electrical signal revealing volume information ofthe liquid drop and spectral signal displaying ingredient information of the liquid individually. Colligate this three kinds of information and after data-processing the fingerprint of the measured liquid can be derived. Due to different characteristics of various liquids, the fingerprint of one liquid differs from that of others. This difference has been proved through experiment. Thus the OLDS is valuable for the discrimination of different liquids and the measurement ofthe liquid's parameters.